Modelling and Control of an End-Over-End Walking Robot

Over the last few decades, Space robots have found their applications in various in-orbit operations. The Canadarm2 and the European Robotic Arm (ERA), onboard the International Space Station (ISS), are exceptional examples of supervised robotic manipulators (RMs) used for station assembly and maintenance. However, in the case of in-space assembly of structures, like Large-Aperture Space Telescope (LAT) with an aperture larger than the Hubble Space Telescope (HST) and James Webb Space Telescope (JWST), missions are still in its infancy; this is heavily attributed to the limitations of current state-of-the-art Robotics, Automation and Autonomous Systems (RAAS) for the extreme space environment. To address this challenge, this paper introduces the modelling and control of a candidate robotic architecture, inspired by Canadarm2 and ERA, for in-situ assembly of LAT. The kinematic and dynamic models of a five degrees-of-freedom (DoF) End-Over-End Walking robot’s (E-Walker’s) first phase of motion is presented. A closed-loop feedback system validates the system’s accurate gait pattern. The simulation results presented show that a Proportional-Integral-Derivative (PID) controller is able to track the desired joint angles without exceeding the joint torque limits; this ensures precise motion along the desired trajectory for one full cycle comprising of Phase-1 and Phase-2 respectively. The gait pattern of the E-Walker for the next phases is also briefly discussed.